Selective enrichment and quantification of okadaic acid in shellfish using an immunomagnetic‐bead‐based liquid chromatography with tandem mass spectrometry assay

Abstract

Okadaic acid is a marine biotoxin that primarily occurs in shellfish and can cause diarrheic shellfish poisoning in humans. When analyzing biological samples using liquid chromatography with tandem mass spectrometry, the presence of complex matrices is a major issue. Thus, it is crucial to selectively and simply extract the target analyte from samples and minimize matrix effects simultaneously. To meet this need, an immunomagnetic‐bead‐based liquid chromatography with tandem mass spectrometry method was developed to detect okadaic acid in shellfish. Magnetic beads bound to monoclonal antibody against okadaic acid were used as affinity probes to specifically enrich okadaic acid in samples, which effectively eliminated matrix effects. A magnetic separator was used to aggregate and separate magnetic particles from sample matrices, and methanol was used to elute okadaic acid from the magnetic beads. Standard solution prepared with methanol was employed directly for quantitative analysis. Several experimental conditions were optimized to improve performance. The method is of interest as a rapid (10 min) sample clean‐up and selective enrichment tool, and it showed good linearity and sensitivity, with reported limits of detection and quantitation of 3 and 10 μg/kg, respectively. Fifty‐three shellfish samples from an aquatic products market were tested using this method, and four samples positive for okadaic acid were found.

Immunoaffinity Extraction and Alternative Approaches for the Analysis of Toxins in Environmental, Food or Biological Matrices

“…Non-covalent binding can also be used to couple Abs to the sorbent. For this purpose, proteins A- [90] or G- [80,99,[104][105][106][107][108] based sorbents or sorbents grafted with anti-IgG [92,98] can be used as these proteins bind a part of the constant region of Abs, allowing the orientation of the Abs with the antigen binding sites away from the surface and towards the solution. The same orientation effect can be obtained using streptavidin activated sorbent that can react with biotinylated Abs [72,79,109].…”

“…This dSPE mode was reported for 34% of the studies cited in Table 2. The particles were prepared by the covalent immobilization of antibodies on NHS-activated Sepharose beads [70], or tosyl-activated magnetic beads [102,110,111] or by non-covalent immobilization on protein G- [80,99,[104][105][106][107][108] or streptavidin- [72,79,109] activated magnetic beads or on amino-coated hollow glass magnetic microspheres [100,101].…”

“…In addition, it is necessary in this mode to optimize the extraction, the desorption times and the vortex speed. It appears that the extraction step takes from 1-10 min [70,72,79,80,100,101,104,105] to 1-2 h [99,102,107,108,110,111], the desorption step being carried out with a similar or shorter time. Most of the procedures include a washing step before desorption to ensure an optimal selectivity, but the duration of this step was never mentioned.…”

“…It consists of using a blank extract of the studied matrix passed through the IS and spiked at different concentration levels to construct a calibration curve. This approach was also proposed by different groups to evaluate the clean-up effect of ISs [38,60,65,68,80]. Indeed, it was considered as necessary for the simultaneous quantification of HT-2 and T-2 toxins in maize and cherry samples [94], of several toxins in cereals [48,54,58,85], feed samples [84], or urine [62].…”

Magnetic Beads in Marine Toxin Detection: A Review

“…IMC combined with LC-MS/MS has also been used by Chen and collaborators [34], in this case for the extraction of OA from shellfish samples. MBs were able to capture the toxin in just 10 min, due to their use of suspension.…”